Radial piston pump with piston-coupling means



May 26, 1970 L. BUDECKER 3,514,224

RADIAL PISTON PUMP WITH PISTONCOUPLING MEANS Filed June 6, 1968 5 Sheets-Sheet 1 4 2b A 4 4d 5 I4 f/ IV lo l 5d' V l LUDWIG BUDECKER 8 2f INVENTOR.

! f BY marl TR ATTORNEY y 1970 1.. BUDECKER 3,514,224

RADIAL PISTON PUMP WITH PISTON-COUPLING MEANS Filed June 6, 1968 3 Sheets-Sheet 2 F G .3 F e .4

MgiRosi ATTORNEY L. BUDECKER May 26, 1970 RADIAL PISTON PUMP WITH PISTON-COUPLING MEANS Filed June 6, 1968 3 Sheets-Sheet 5 FIG.?

FIG.9

LUDWIG BUDECKER INVENTOR.

BY R095 ATTORNEY United States Patent 3,514,224 RADIAL PISTON PUMP WITH PISTON-COUPLING MEANS Ludwig Budecker, Frankfurt, Germany, assignor to Alfred Teves GmbH, Frankfurt am Main, Germany, a corporation of Germany Filed June 6, 1968, Ser. No. 735,149 Claims priority, application Germany, June 24, 1967,

Int. ci. F04b 1/04, 53/04,- F16l1 25/08 U.S. C]. 417-273 6 Claims ABSTRACT OF THE DISCLOSURE A radial-piston pump with a coupling-ring assembly wherein each coupling ring interconnects two diametrically opposite pistons for joint operation by an eccentric shaft; the rings have bifurcated lugs received in circumferential recesses provided in the pistons, and in formfitting engagement with the pistons.

My present invention relates to a radial-piston pump and, more particularly, to a radial-piston pump having a plurality of radially reciprocable pistons interconnected by one or more coupling rings and operated by an eccentric shaft in order to displace a fluid.

In pumps of this type the pistons must be perfectly coordinated so that the hydraulic fluid is correctly routed on its Way from a fluid reservoir to the intake chambers of the various piston cylinders. A number of systems have been proposed in prior art to effect such piston coordination. The commonly assigned US. Pat. 3,259,074 describes tie or coupling rings interconnecting diametrically opposite pistons in such a pump to eifect their joint movement, so that one is subject to the compression stroke while another is engaged in the fluid-intake stroke. Such coupling rings are lodges in circumferential recesses of the pistons so that the plane of each ring lies within the outlines of the respective pistons and has a tendency to oscillate slightly with piston movements. Unless the grooves and rings are carefully dimensioned the rings are apt to slip out of their respective grooves.

It is therefore the primary object of my invention to extend the principles of the aforementioned patent still further and to provide a radial-piston pump wherein coupling rings and pistons are securely interconnected with out danger of dislodgement.

Another object is to provide improved means for linking coupling rings and pistons, especially rings which are inexpensive and easy to install.

These objects and others which will become apparent hereinafter are attained, in accordance with the present invention, by providing the coupling rings, which are designed to lie in planes perpendicular to the pump axis and parallel to the piston array, with a plurality of axially extending projections for engaging the pistons. In a preferred embodiment each coupling ring has a substantially rectangular cross-section and projections perpendicularly extending therefrom. The projections may be formed as lugs (stamped out in one piece) on the ring and subsequently bent through 90.

According to another version of my invention the pins, fabricated separately, are attached to the coupling ring by welding, screws or rivets. A plurality of coaxially arranged coupling rings may be provided on one side of a planar piston array to engage simultaneously a pair of diametrically opposite pistons disposed about the stationary cylinder block of the radial piston pump. Since the array may include several pairs of pistons, a corresponding number ice of rings are provided, the rings being closely stacked axially and occupying minimum space. The lugs of the rings most distal from the array of pistons reach around the proximal rings and are longer by at least the thicknesses of the proximal rings. Each coupling ring includes formations of a specific and distinctive length to engage overlappingly specific pistons in the arrangement. When several rings are used jointly, their position relative to the eccentric shaft regulates the return stroke of the pistons which need not be symmetrically paired on opposite sides of the cylinder block but may be arrayed in any predetermined number and order about its circumference. No additional space is required when several coupling rings are used jointly, since each ring is made of a very thin sheet of material. Thus a series of rings can be stacked axially and still be considered to be lying in a plane.

The above and other objects, features and advantages of my invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is an axial cross-sectional view through a radialpiston pump, partly broken away, according to my invention;

FIG. 2 is a transverse cross'sectional view taken along the line IIII of FIG. 1;

FIG. 3 is an elevational view of a coupling-ring blank adapted to be used to form the ring for the radial-piston pump of FIGS. 1 and 2;

FIG. 4 is a side view of the coupling-ring blank shown in FIG. 3;

FIG. 5 is an elevational view of the coupling ring made from the blank of FIG. 3;

FIG. 6 is a side view of the coupling ring shown in FIG. 5;

FIG. 7 is a perspective exploded view of another coupling-ring assembly;

FIG. 8 is a cross-sectional view taken along the line VlII-VIII of the assembly; and

.FIG. 9 shows another method of making the ring in a perspective view.

In FIG. 1, I show a stationary cylinder block 1 to which a pair of end plates 2 and 3 are attached by the usual bolts 3a, the end plate 3 being formed with a central opening 3b through which an eccentric shaft 4 extends, the shaft being sealed at 30 to prevent leakage of fluid around the shaft.

The end plate 2 is formed with an axially open recess 2a which defines with the other end of shaft 4 a chamber 2b lying in a plane perpendicular to the axis A of rotation of the shaft. A fluid-intake port 2c is formed in the end plate 2 and communicates with the chamber 2d which is sealed against fluid leakage by a sealing ring 2b seated against an internal shoulder 1a of the cylinder block 1. A bearing ring 14 centers the shaft within the cylinder block. The seal 2d is fitted onto a cylindrical boss 22 surrounding the chamber 2b and defining with the end face 112 of the cylinder block 1 an annular collecting channel 10 connected by passages 1d and 1d (FIG. 1) with radial cylinder bores 1e and 1e, respectively.

At least two such diametrically opposite cylinder bores 12 or 1e are provided in each of two planes P and P spaced apart along the axis A and perpendicular thereto. As will be apparent from FIGS. 7 and 8, a plurality of pairs of cylinder bores may be provided in each of these axially spaced planes. The cylindrical bores 12 and 1e are all closed by plugs 11, 1g with the exception of the radial bore 1g serving as the fluid outlet port of the pump. The pistons 5, 5 and 6, radially reciprocable in the cylinder bores 16 and 1e, have pumping heads as shown at 5:1 defining pumping chambers 5b in the cylinder bores radially outwardly of these pistons and between the latter and respective check valves e which allow outward fluid flow only.

Annular grooves 12 and 12' in the pistons separate the pumping heads 5a from the shanks 5c of the pistons which bear upon a bushing 7 surrounding an eccentric portion 4a of the shaft as described in my co-pending application Ser. No. 712,817, filed Mar. 13, 1968, to provide improved cooling and lubrication of the eccentric and its shaft. The pumping chamber 5b, 6b communicate with annular channels 2] and 3], respectively, by axially extending bores 5d and 6d (FIG. 1) which are closed by radially outward advance of the pistons to confine fluid in the chambers 5b.

The hydraulic fluid is delivered to channel 2f from the chamber 212 mentioned earlier and the inlet 20. Channel 3] receives fluid from the inlet 20 via an axially extending bore 4b in the shaft 4, opening at the chamber 2b, from which a plurality of radial bores 40 lead into the chamber 4d surrounding the sleeve 7. The latter is provided with a plurality of openings 7a, 7b and 7c (see application Ser. No. 712,817) past which fluid can flow from the bores 4c into the annular chamber 4d. From the latter, a passage 1h leads into the annular clearance 11' between the cover plate 3 and the cylinder 1 and thence into the channel 3 communicating with the bores 6b of the pistons arrayed along the plane P.

The pump shown in FIGS. 1 and 2 operates generally as described in my aforementioned co-pending application. Upon rotation of the shaft 4, the pistons 5, 5 6, etc. are radially reciprocated. As the pistons move radially inwardly (as shown for the piston 5 in FIG. 1), fluid is drawn from the chamber 2b and the passage 2) or the passages 4b, 40, 70-70, 4d, 1h, 11' and 3 into the chambers 5b, 5b, 6b ahead of the pistons 5, 5' and 6. As the pistons are forced radially outwardly with continued rotation of the shaft 4, the leading edges of the pumping heads 5a block escape of the fluid from the chambers 5b etc. so that the fluid therein is forced past the check valves, collected in the annular groove 1c and delivered via the passage 1d to the outlet port connected with the load.

In accordance with the principles of this invention, and the aforementioned commonly assigned patent, at least one coupling ring 8 or 9 is provided for each planar array of pistons 5, 5' or 6. The coupling rings 8 and 9 have axially extending formations 10 (shown in greater detail in FIGS. 3 through 5) and are radially shiftable in the chambers 2 and 3f lying perpendicular to the axis A of the shaft to the right-hand and left-hand sides of the pistons 5 and 5' and the pistons 6, respectively.

From FIG. 2, it can be seen that the channel 2 may have a pair of parallel flanks 2f and 2f" guiding the ring coupling the diametrically opposite pistons 5 for joint radial movement in the direction represented by the arrow R. When the piston 5 is shifted to the right in its compression stroke, the piston 5, whose groove 12' receives the formation 10' of the coupling ring 8, is likewise shifted to the right during its intake stroke, thereby allowing fluid to flow from the bore 5d into the pumping chamber 5b ahead of the piston 5. Continued rotation of the eccentric reverses the sequence and draws the piston 5 radially to the left While driving the piston 5 to the left during its compression stroke. Separate springs are thus not required to retain the pistons against the bushing 7.

From FIGS. 3 and 4, it can be seen that the coupling ring 8 can be made from a blank 8' stamped from sheet metal so that the formations 10 and 10, adapted to be received in the grooves 12 and 12', are constituted as bifurcated lugs lying in the plane of the ring. These lugs may be bent axially (FIGS. 5 and 6), to form the bifurcations hugging the pistons 5 and 5' in their respective grooves.

As indicated in FIG. 6, the lugs 10 and 10' converge axially inwardly toward the axis A with half-angles 0c of several degrees. When the rings are placed in the grooves 21 and 3 their lugs 10 and 10 can be deflected slightly outwardly to bias the pistons resiliently (i.e. with the spring force inherent in the deflection of the lugs) against the eccentric sleeve 7. Instead of forming the lugs integrally with the rings, the system diagrammatically illustrated in FIG. 9 can be used. In this case, the ring 8a is shown to be provided with a bifurcated lug, partly broken away, which has :an angularly bent portion 10a attached by a rivet 10a" to ring 8a. The rivet 10a" may represent any means for attaching a separate lug to the ring 8a, including welds, solder, bolts or the like.

In FIGS. 7 and 8, I show a modification of the present invention wherein a plurality of pairs of pistons are provided in each plane, e.g. the plane P. In this arrangement, four pistons 105, 205, 205 are provided in pairs diametrically opposed about the axis A, but in a common plane perpendicular to this axis. Corresponding to the number of pairs of pistons in each planar array, an equal number of coupling rings 108, 208 are provided (FIG. 8) so that the lugs and 110' of ring 108 engage in the annular grooves 112 and 112' of pistons 105 and 105', while another pair of lugs 210 and 210' reach past the ring 108 and, formed on a more remote ring 208, enter the grooves 212 and 212' of the pistons 205, 205. The lugs 210' have axial lengths L which exceed the axial length 11 of the lugs 110 and 110' by a distance equal to the thickness of the ring 108 or, when a number of rings are provided ahead of the ring 208, to the thickness of the stack of rings. As a consequence, a highly compact arrangement is created with a re atively large number of coupling rings.

I claim:

1. A radial-piston pump comprising a cylinder block with an intermediate body and a pair of end members bracketing said body, the latter being fonmed with two pairs of diametrically opposite radial bores located in two axially spaced transverse planes, a shaft journaled in said body for rotation about its axis and passing outwardly through one of said end members, said cylinder block being formed with inlet and outlet ports for a working fluid and with connecting passages for said fluid including a pair of axially spaced annular channels formed around said shaft between adjacent faces of said body and said end members, a first and a second coplanar pair of diametrically opposite radial pistons provided with annular grooves and lodged in said pairs of radial bores between said annular channels, said shaft having an eccentric portion engaged by said pistons for radially reciprocating same, said pistons defining variable-volume pumping chambers in said bores communicating via the respectively proximal annular channel with said ports, :and a pair of flat coupling rings respective y disposed in said annular channels with freedom of limited radial displacement therein, said rings being provided with axially extending bifurcated lugs positively engaging the pistons of an adjoining pair by being received in said annular grooves thereof for synchronizing their motions.

2. The pump defined in claim 1 wherein said lugs are formed integrally with said rings.

3. The pump defined in claim 1 wherein said lugs are inclined toward said axis and are resiliently deflectable to urge said pistons against said shaft.

4. The pump defined in claim 1 wherein said shaft has a sleeve mounted on said eccentric portion with clearance and lubricated by said fluid.

5. The pump defined in claim 1 wherein said body is formed with another pair of diametrically opposite bores in one of said planes, further comprising another pair of pistons in said other pair of bores bearing upon said eccentric portion and defining other variable-volume pumping chambers in said other pair of bores communieating with an adjoining one of said annular channels, and an additional flat coupling ring in said adjoining one of said channels juxtaposed with one of the firstmentioned coupling rings therein with freedom of limited radial displacement, said additional ring having ax- 2,693,150 11/1954 Pickard et a1 103-174 6 Edelman et a1. 103-162 Seweil 103-174 Engle 74-55 Lucien et a1. 103-124 Bacaer 103-161 X WILLIAM L. FREE-H, Primary Examiner US. Cl. X.R. 

